This invention is directed to a polymer blend containing polyvinyl chloride, two chlorinated elastomers, i.e., chlorinated polyethylene elastomers and/or chlorosulfonated polyethylene elastomers wherein the chlorinated elastomers have different chlorine levels, and certain ethylene-containing terpolymers. The resulting polymer blend shows a significant enhancement in oil swell resistance, and improved low temperature toughness.
Polyvinyl chloride has been blended with chlorinated polyethylene and chlorosulfonated polyethylene in an attempt to improve the physical properties of the polyvinyl chloride. The blending approach has been utilized in an attempt to fulfill the increasing need for polymers that are melt processible, have good mechanical strength, chemical and oil resistance, high impact resistance, and good low temperature properties. However, because of inherent deficiencies of the system, many blends suffer critical property shortcomings such as an inadequate balance between oil swell resistance and low temperature toughness, which limits commercial applications for the compositions. It is thought that the fundamental cause of the problem is the insufficient interphase stability of the blend system due to the inadequate physical compatibility between the component polymers. There is a need in the industry for an elastomeric blend of polymers having a combination of outstanding resistance to oil swell balanced with superior low temperature properties.